%%
%% The LaTeX Companion, 3ed
%%
%% Example 1-3-4 on page I-17 in "Typographic conventions".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3examargin}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{159.0pt}

%StartShownPreambleCommands
\usepackage[leqno]{amsmath}
%StopShownPreambleCommands

\begin{document}
\begin{equation} (a+b)^2 = a^2+2ab+b^2 \end{equation}
\end{document}
